A program that is written to run under the Microsoft Windows operating system, also called a "Windows app." All 32-bit Windows applications run in the 32-bit and 64-bit versions of Windows. Any 64-bit applications (there are few by comparison) require 64-bit Windows, which is the standard on most modern desktop and laptop PCs. Older 16-bit Windows applications can run in the 32-bit versions of Windows, including Windows 95, 98, XP, Vista, 7 and 8. However, 16-bit applications do not run in the 64-bit versions of Windows (see Windows XP Mode and NTVDM). Windows Tablet Applications Most applications that run in the 32-bit desktop versions of Windows will run in Windows 8 tablets, but not Windows RT tablets. See Windows 8 tablet.